Shared waters, shared challenges: unlocking the path to transboundary basin sustainability

Across the world, rivers that cross national borders are lifelines for billions—yet they are under far greater strain than water systems contained within one country. A sweeping new analysis of 310 transboundary basins worldwide finds their average Sustainable Development Goals (SDGs) Index score is just 42 out of 100, well below the global national average of 67. Using a novel framework that blends environmental inequality metrics with SDG performance, researchers identified four distinct challenge types, from degraded water quality to vulnerability to climate extremes. The study reveals that tackling clean water, economic growth, and health together could help 38% of these shared basins achieve sustainability.

Transboundary basins knit together countries through shared waters, ecosystems, and economies. They provide food, energy, and biodiversity, but also demand complex governance that often falters under competing national priorities. Climate change, rising populations, and land-use shifts intensify upstream–downstream tensions, while political instability and conflict can derail cooperation. Many assessments overlook these cross-border dynamics, focusing instead on national averages that hide basin-level inequalities. Based on these challenges, there is an urgent need for a global, systematic approach that captures the realities of shared river systems—one that can guide policymakers toward interventions that address both environmental and social dimensions across borders.

A research team from Nanjing University, the Chinese Academy of Sciences, and Stockholm University has delivered the first comprehensive global assessment of Sustainable Development Goals (SDG) progress in transboundary basins. Published (DOI: 10.1016/j.ese.2025.100611) in August 2025, in Environmental Science and Ecotechnology, the study introduces a framework that integrates Environmental Gini coefficients (EGCs)—measuring resource inequity—with 98 SDGs indicators. The results reveal striking regional contrasts, from basins in Africa scoring as low as 13 to European rivers surpassing 75. The analysis points to coordinated action on clean water, economic growth, and health as the most effective route to boosting sustainability in these shared waters.

The researchers built a four-step framework to capture basin-level realities. They first mapped high-resolution water availability and socio-environmental data, then calculated EGCs to quantify inequalities between upstream and downstream regions. These EGCs were combined with SDG Index data to produce composite scores for each of the 310 basins.

Clustering revealed four distinct profiles: Institutional governance basins (e.g., Amur, Yukon) with relatively strong governance but in need of deeper cooperation; Sustained growth basins (e.g., Niger) burdened by poor water quality, poverty, and disease; Inclusive growth basins (e.g., Seine, Rhine–Meuse) balancing economic strength with environmental pressures; and Social coordination basins (e.g., Amazon, Mekong) highly exposed to floods and droughts.

Scenario modeling showed limited gains from achieving clean water (SDG 6) alone—only 17 basins would reach sustainability. Combining SDG 6 with economic growth (SDG 8) raises that share to 17%, while achieving SDGs 3, 6, and 8 together could elevate 38% of basins into sustainability. The findings underscore that multi-goal, basin-specific strategies offer far greater potential than isolated interventions.

"Our work exposes a hidden layer of inequality in shared water systems that national statistics simply don't capture," said lead author Yiqi Zhou. "By marrying measures of environmental equity with SDG performance, we've mapped where cooperation can deliver the greatest returns. The message is clear—single-goal efforts are insufficient. Coordinated progress on clean water, economic growth, and public health is vital for sustainable futures in transboundary basins. This framework equips policymakers with a clearer view of both the challenges and the levers for change."

The framework offers a decision-making compass for governments, basin authorities, and international agencies. By pinpointing where resource inequities align with socio-economic shortfalls, it can guide targeted investments in infrastructure, governance reforms, and cross-border agreements. The results suggest that aligning efforts across clean water, livelihoods, and health yields the greatest overall gains. Applied at the basin scale, such integrated strategies could help ease geopolitical tensions, fortify resilience against climate shocks, and accelerate progress toward multiple SDGs. For some of the world's most sensitive shared rivers, this could mean the difference between escalating conflict and sustainable cooperation.

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References

DOI

10.1016/j.ese.2025.100611

Original Source URL

https://doi.org/10.1016/j.ese.2025.100611

Funding information

Funding support for this work has been provided by the Major Projects of the National Social Science Foundation of China (23&ZD099), National Natural Science Foundation of China (42201301), Special Foundation of Science and Technology Innovation of Carbon Peak and Carbon Neutrality in Jiangsu Province (BK20220037), the "GeoX" Interdisciplinary Research Funds for the Frontiers Science Center for Critical Earth Material Cycling, Nanjing University (0209/14380116), the Special Fund of Jiangsu Province Carbon Peak and Carbon Neutral Technology Innovation (BK20220037), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX24_0198), and the Swedish Research Council (VR, project 2022–04672).

About Environmental Science and Ecotechnology

Environmental Science and Ecotechnology (ISSN 2666-4984) is an international, peer-reviewed, and open-access journal published by Elsevier. The journal publishes significant views and research across the full spectrum of ecology and environmental sciences, such as climate change, sustainability, biodiversity conservation, environment & health, green catalysis/processing for pollution control, and AI-driven environmental engineering. The latest impact factor of ESE is 14.3, according to the Journal Citation Reports^TM 2024.